Passengers told Schneider they literally felt the train jump, and then it came to a screeching halt.

The derailment happened on the elevated stretch of the line over Broadway near 125th Street, just north of the Columbia University campus. As WCBS 880’s Peter Haskell reported Wednesday night, the train was headed south from the 125th Street station when it derailed.

“It sounded like when a brick would fall, and just, ‘boom,’” said Sonia Proctor, a passenger on the train. “You know, that’s the way it sounded, because it went, ‘coomp!’”

Added passenger Dwight Bowerbank of Morningside Heights: “Before it came to a halt, there was a jump in the train, the train actually jumped. The lady that was beside me, her son jumped and fell out of the seat, then it came to a screeching halt.”

Bowerbank said he was in the third car back, and captured the whole scene on his smartphone as firefighters came aboard.

He said when he looked out the windows he saw something suspicious.

“There was a piece of wood that was stuck under the wheel in my car,” he said, adding that the wood “obviously” was not supposed to be there.

Passenger “jamie_bx” documented the incident on Twitter. She first wrote that the train had been “stuck for longer than I’ve ever experienced” and was surrounded by fire trucks and helicopters. The train announcer first said the delay was due to an “investigation,” but after about 20 minutes, the train powered down and the air conditioning shut off, jamie_bx reported.

Soon after, an announcement came that the train might have to be evacuated, jamie_bx reported, adding some people made phone calls saying, “I’m not gonna make it,” while people snapped photos and videos.

The MTA sent a rescue train, but since all power was shut off it could not make it down the tracks. Thus, it took more than an hour to get a rescue train to connect the stranded subway to the station platform and get everyone out.

Finally, the train was evacuated.

“The trains came up one by one and they put a platform between the trains,” said Jessica Feliciano of Morningside Heights.

One by one the passengers climbed out of the train, and came down the station stairs.

No injures were reported. Many passengers were interviewed by detectives once they got off in Harlem.

A derailment shut down the No. 1 line in Upper Manhattan Wednesday. (Credit: jamie_bx, via Twitter)

Officials said the derailment may have been caused by a cracked rail, Haskell reported. But no final cause was immediately pinpointed, and it was not clear whether the piece of wood on the tracks that Bowerbank mentioned played a role.

Investigators were still on the scene as of 11 p.m., and could stay all night, FDNY officials said.

“It’s going to be out of service for a while,” said FDNY Chief Dan Donoghue. “They had the derailment. They’re going to have to figure out why it derailed and what’s wrong with the rails, so the southbound train is going to be out for a while. I don’t know how long.”

No. 1 trains were running from 137th Street-City College to Van Cortlandt Park-242nd Street in the Bronx. Trains also continued to run between Chambers Street and South Ferry in Lower Manhattan.

To make up for the lost service, No. 2 and 3 trains were running locally between Chambers Street and 96th Street. But passengers in need of stops between 96th and 137th streets would have to switch to the A or C line a short distance to the east, or take shuttle buses running between the two stops.